can adding gravel and live plants cause "mini cycle"?

This is a discussion on can adding gravel and live plants cause "mini cycle"? within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; -->
added 35lbs of gravel to my 55 gallon yesterday,(didn't remove any) and added 5 stems of italian val,water sprite and an ancharis. I had ...

added 35lbs of gravel to my 55 gallon yesterday,(didn't remove any) and added 5 stems of italian val,water sprite and an ancharis. I had to remove 4 plastic plants but kept the others in there. Today was water day change and tested water before changing and had .25 amm and .25 nitirite,hadn't had readings on those since the tank was finally cycled 5 months ago. So I did a 50% WC instead of my normal 25% and it took care of the readings. What could have caused this ? I feed once a day. Stock is 3 platies,6 cherry barbs and 5 zebra danios.

Not certain what would have caused the change. Adding live plants should help the issue, not casue a mini cycle!
Now, if you buried your already "active" gravel with a thick layer of new gravel, that could be the problem. A layer of new gravel may have caused an anaerobic condition or limited water flow to the established bacterially seeded gravel layer, cutting down the tank's ability to process waste.